/Engine/Source/Runtime/MovieScene/Public/Evaluation/MovieSceneEvaluationField.h
Diff the active entities (tracks and sections) this frame, with the specified previous frame's meta-data
void DiffEntities ( const [FMovieSceneEvaluationMetaData](API\Runtime\MovieScene\Evaluation\FMovieSceneEvaluationMetaData) & LastFrame, [TArray](API\Runtime\Core\Containers\TArray)< [FMovieSceneOrderedEvaluationKey](API\Runtime\MovieScene\Evaluation\FMovieSceneOrderedEvaluationKey) > * NewKeys, [TArray](API\Runtime\Core\Containers\TArray)< [FMovieSceneOrderedEvaluationKey](API\Runtime\MovieScene\Evaluation\FMovieSceneOrderedEvaluationKey) > * ExpiredKeys ) const